Comparative evaluation of fire resistance of partition wall blocks prepared with waste materials

Partition wall blocks produced by using recycled concrete as aggregates may be exposed to fire conditions in real applications. It is of great significance to keep the thermal conductivity of the block as low as possible to minimize damages due to the outbreak of a fire. To do so, alternative and/or additional materials can be used in the preparation of the blocks, which can reduce the heat transfer rate with little degradation of strength. In this study, three kinds of waste materials derived from construction and demolition (C&D) waste were respectively used to add or replace fine aggregates by volume or weight, including polypropylene fiber (PP fiber), recycled glass (RG) and recycled polystyrene (RP) in preparing the partition blocks. The compressive strength, water absorption, density, thermal conductivity, porosity of the blocks before and after exposure to elevated temperatures of 300 °C, 500°Cand 800 °C were examined. The results indicated that at room temperature, the incorporation of PP fibers had negligible influence on the physical properties of the blocks with little reduction of compressive strength, while the replacement of fine aggregate by RP resulted in significant reduction in compressive strength as well as thermal conductivity. The use of RG as a fine aggregate could reduce the thermal conductivity without significant effects on the compressive strength of the block samples. Although the exposure to elevated temperatures brought about reduction in thermal conductivity, the increase in porosity led to a large reduction in compressive strength of the blocks prepared with RP. The most significant finding of the study was that using 100% RG as fine aggregate was beneficial to conservation of compressive strength especially after exposure to 800 °C due to the re-solidification of the melted RG upon cooling, which led to a better thermal insulation property of the blocks. A further study on the influence of RG on compressive strength based on the mortar blocks prepared with glass cullet as fine aggregates convincingly proved the improved fire resistance of using 100% RG especially after 800 °C. The use of RG for partition blocks production has significant advantages in terms of sustainability and fire resistance.